Design of an X-ray FEL undulator
- Stanford Synchrotron Radiation Laboratory, Stanford Linear Accelerator Center, Stanford, California 94309 (United States)
An undulator designed to be used for an x-ray free electron laser has to meet a set of stringent requirements. With no optical cavity, an x-ray FEL operates in the single pass Self Amplified Spontaneous Emission (SASE) mode; an electron macropulse is microbunched by an undulator and the radiation it creates. The microbunched pulse emits spontaneous radiation and coherent FEL radiation, whose power may reach saturation in a sufficiently long and perfect undulator. The pulse must have low emittance and high current, and its trajectory in the undulator must keep the radiation and the pulse together with a very high degree of overlap. In this paper we use the case of the Linear Coherent Light Source (LCLS) x-ray free electron laser to illustrate design concepts for long free electron laser undulators. The LCLS is intended to create 1.5 A x-rays using an electron beam with 15 GeV energy, 1.5{pi} mm-mrad normalized emittance, 3400 A peak current, and 280 fsec FWHM bunch duration. According to our simulations, this 2{sigma}{sub r}=65 mm rms diameter beam must overlap its radiation with a walkoff of no more than 5 {mu}m RMS per 11.7 meter field gain length for efficient gain. The energy spread of the beam is {sigma}{sub E}=0.0002 E{sub e}. This places severe limitations on the magnetic field errors and on mechanical tolerances. In this paper we shall discuss how to meet these requirements.
- OSTI ID:
- 21175519
- Journal Information:
- AIP Conference Proceedings, Vol. 413, Issue 1; Conference: Workshop on single pass, high gain FELs starting from noise, aiming at coherent x-rays, Garda Lake (Italy), 2-7 Jun 1997; Other Information: DOI: 10.1063/1.54426; (c) 1997 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
Similar Records
Design of an x-ray free electron laser undulator
Design of an x-ray free electron laser undulator